More than 4,200 cardiac arrests happen outside of hospital every year; this is where someone’s heart stops beating and starts dying.
You can find defibrillators in many public places and also locate your nearest one via defibfinder.uk
Paramedic, Dave Hawkins, explains how to recognise someone who has had a sudden cardiac arrest.
https://audioboom.com/posts/8656498-paramedic-dave-hawkins